Humans and most other living things on Earth exhibit physical, mental, and behavioral changes in response to the presence or absence of light in the surrounding environment throughout the 24-hour cycle of the day. These changes, known as circadian rhythms, can influence sleep/wake cycles and other important bodily functions. In humans, when the body's eyes take in less light at night, the body's suprachiasmatic nucleus (SCN) receives information about the reduction in incoming light and instructs the brain to increase production of the hormone melatonin, normally resulting in drowsiness and eventually sleep. Conversely, as light levels increase in the daytime, the SCN instructs the brain to produce less melatonin, normally resulting in wakefulness and a degree of alertness through the day.
These and other features of the present embodiments will be understood better by reading the following detailed description, taken together with the figures herein described. The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures may be represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing.